Miscellaneous. 471 



these by the friction of the pharyngeal bones; the Orthagorisci 

 cause them by the friction of their intermaxillary teeth ; various 

 Cyprinoidei, Anguilliformes, Siluroidei, &c. cause them by expelling 

 into the oesophagus the air of their swimming-bladder. 



Lastly, there are noises which, while regular and voluntary, like 

 the preceding, result from certain peculiarities presented by muscles 

 in course of contraction in fishes furnished with an air-bladder 

 which has no communication with the oesophagus. These have been 

 observed in Perlstedion cataphracta, Trigla, Scicena, Zeus, Umbrina 

 cirrhosa, and Hipjiocampus brevirostris. 



The mechanism of the production of the first two varieties of 

 these sounds was already pretty well known ; but M. Dufosse, by a 

 fresh examination and by his dissections, has given more precision 

 to several of the anatomical and physiological notions relating to it. 

 This part of his investigations, which is already old, has, moreover, 

 been the subject of a favourable report from our regretted colleague, 

 Constant Dumeril (see ' Comptes Rendus,' 1858, tome xlvi. p. 610). 

 Therefore we will dwell only upon the later communications of the 

 author, made from 1858 to 1862 (Comptes Eendus, 1862, tome Ixiv. 

 p. 393), which appear to us to be stiU more valuable than the pre- 

 ceding ones. 



He has set himself to show, that the regular somids which fishes 

 emit may be voluntarily produced, and are not a simple consequence 

 of some other physiological action. They are consequently, in cer- 

 tain cases, true acts of expression, however rudimentary. 



M. Dufosse has shown that in the fishes which voluntarily pro- 

 duce regular sounds, these are commensurable as musical sounds ; 

 and although they are more imperfect than those emitted by ser- 

 pents, as Lacepede had already remarked, he has determined their 

 note in all the species which he has observed. He has also shown, 

 by conclusive experiments, that all the fishes which emit noises or 

 regular expressive sounds in the air, produce them also in the water — 

 that is to say, in the medium in which they live and are naturally 

 in relation to each other. 



In the case of several species, the intensity of the sounds is so 

 great that, when produced by a single individual, they may be heard 

 at a distance of several metres ; this is the case with certain Triglce, 

 Zeus, and especially Pogonias cliromis, &c. When emitted by 

 animals combined in shoals, they may be transmitted stUl further ; 

 more than once, under these conditions, they have frightened the 

 crews of ships, who did not know to what cause to ascribe the noises 

 produced around and beneath their vessels. They have been the 

 source of more than one fable spread among maritime populations. 

 M. Dufosse has himself ascertained the existence of these noises, by 

 going frequently, and not always without danger, to pass whole nights 

 on the open sea in fishing-boats. 



In the case of the fishes with an air-bladder which does not com- 

 municate with the oesophagus, M. Dufosse has ascertained experi- 

 mentally that the wall of this reservoir was afi'ected by strong and 

 frequent movements during the production of the sounds. He has 

 thoroughly studied the nerves and muscles then in action. His 



